Mixtures containing a gold thiolate are known from the prior art. They may be used to decorate substrates by applying them to the substrate surface and subsequent graining (see, for example, U.S. Pat. No. 3,391,010, DE 1421865 A and DE 4122131 C1). There is an increasing desire to apply decorative preparations using a nozzle, such as by inkjet printing. In this context, it has been found that the application of the mixtures known from the prior art using a nozzle, in particular in the course of inkjet printing, is associated with the gold thiolates in the mixture being reduced on the metal parts of the applicator, such as the inkjet printer, contacting the mixtures. As a result, the metal parts of the applicator become coated with gold. Due to this lack of corrosion resistance, the applicator becomes contaminated and ultimately is no longer usable. Moreover, the amount of gold deposited on the metal parts of the applicator is no longer available for decoration of the substrates, which has a disadvantageous effect on the decoration thus produced. Moreover, it has been found that graining these mixtures often leads to a matte purple-colored layer rather than the desired glossy layer. Moreover, at least partial segregation during storage is a problem encountered with many mixtures known from the prior art. Unstable mixtures of this type are not suitable for application through a nozzle, in particular using an inkjet printer.
Alternative methods for decoration of substrates are also known from the prior art. For example, WO 00/73540 A1 describes a process in which an aqueous gold solution is used to deposit gold in a galvanic gold bath. Moreover, an aqueous solution of a gold thiolate compound is applied onto a ceramic in WO 00/10941 A1 in order to obtain a colored decoration by heating.
However, the prior art does not describe any way in which a gold compound may be applied onto a substrate by targeted and variable application using a nozzle, such as, for example, by inkjet printing.